Annotation of src/usr.bin/ssh/sshconnect1.c, Revision 1.74
1.74 ! djm 1: /* $OpenBSD: sshconnect1.c,v 1.73 2014/01/27 19:18:54 markus Exp $ */
1.1 markus 2: /*
3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
8: *
1.6 deraadt 9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.1 markus 14: */
15:
1.69 deraadt 16: #include <sys/types.h>
17: #include <sys/socket.h>
1.1 markus 18:
19: #include <openssl/bn.h>
1.66 stevesk 20:
1.68 stevesk 21: #include <stdio.h>
1.67 stevesk 22: #include <stdlib.h>
1.66 stevesk 23: #include <string.h>
1.69 deraadt 24: #include <signal.h>
25: #include <pwd.h>
1.1 markus 26:
1.69 deraadt 27: #include "xmalloc.h"
1.18 markus 28: #include "ssh.h"
29: #include "ssh1.h"
1.1 markus 30: #include "rsa.h"
31: #include "buffer.h"
32: #include "packet.h"
1.69 deraadt 33: #include "key.h"
34: #include "cipher.h"
1.58 djm 35: #include "kex.h"
1.1 markus 36: #include "uidswap.h"
1.18 markus 37: #include "log.h"
1.1 markus 38: #include "readconf.h"
1.4 markus 39: #include "authfd.h"
1.1 markus 40: #include "sshconnect.h"
41: #include "authfile.h"
1.57 djm 42: #include "misc.h"
1.18 markus 43: #include "canohost.h"
1.69 deraadt 44: #include "hostfile.h"
1.37 dugsong 45: #include "auth.h"
1.73 markus 46: #include "digest.h"
1.1 markus 47:
48: /* Session id for the current session. */
1.13 markus 49: u_char session_id[16];
50: u_int supported_authentications = 0;
1.1 markus 51:
52: extern Options options;
53: extern char *__progname;
54:
55: /*
56: * Checks if the user has an authentication agent, and if so, tries to
57: * authenticate using the agent.
58: */
1.35 itojun 59: static int
1.24 itojun 60: try_agent_authentication(void)
1.1 markus 61: {
1.5 markus 62: int type;
1.1 markus 63: char *comment;
64: AuthenticationConnection *auth;
1.13 markus 65: u_char response[16];
66: u_int i;
1.5 markus 67: Key *key;
68: BIGNUM *challenge;
1.1 markus 69:
70: /* Get connection to the agent. */
71: auth = ssh_get_authentication_connection();
72: if (!auth)
73: return 0;
74:
1.43 markus 75: if ((challenge = BN_new()) == NULL)
76: fatal("try_agent_authentication: BN_new failed");
1.1 markus 77: /* Loop through identities served by the agent. */
1.5 markus 78: for (key = ssh_get_first_identity(auth, &comment, 1);
1.42 deraadt 79: key != NULL;
80: key = ssh_get_next_identity(auth, &comment, 1)) {
1.1 markus 81:
82: /* Try this identity. */
83: debug("Trying RSA authentication via agent with '%.100s'", comment);
1.71 djm 84: free(comment);
1.1 markus 85:
86: /* Tell the server that we are willing to authenticate using this key. */
87: packet_start(SSH_CMSG_AUTH_RSA);
1.5 markus 88: packet_put_bignum(key->rsa->n);
1.1 markus 89: packet_send();
90: packet_write_wait();
91:
92: /* Wait for server's response. */
1.47 markus 93: type = packet_read();
1.1 markus 94:
1.62 djm 95: /* The server sends failure if it doesn't like our key or
1.1 markus 96: does not support RSA authentication. */
97: if (type == SSH_SMSG_FAILURE) {
98: debug("Server refused our key.");
1.5 markus 99: key_free(key);
1.1 markus 100: continue;
101: }
102: /* Otherwise it should have sent a challenge. */
103: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
104: packet_disconnect("Protocol error during RSA authentication: %d",
105: type);
106:
1.46 markus 107: packet_get_bignum(challenge);
1.45 markus 108: packet_check_eom();
1.1 markus 109:
110: debug("Received RSA challenge from server.");
111:
112: /* Ask the agent to decrypt the challenge. */
1.5 markus 113: if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) {
114: /*
115: * The agent failed to authenticate this identifier
116: * although it advertised it supports this. Just
117: * return a wrong value.
118: */
1.53 itojun 119: logit("Authentication agent failed to decrypt challenge.");
1.74 ! djm 120: explicit_bzero(response, sizeof(response));
1.1 markus 121: }
1.5 markus 122: key_free(key);
1.1 markus 123: debug("Sending response to RSA challenge.");
124:
125: /* Send the decrypted challenge back to the server. */
126: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
127: for (i = 0; i < 16; i++)
128: packet_put_char(response[i]);
129: packet_send();
130: packet_write_wait();
131:
132: /* Wait for response from the server. */
1.47 markus 133: type = packet_read();
1.1 markus 134:
135: /* The server returns success if it accepted the authentication. */
136: if (type == SSH_SMSG_SUCCESS) {
1.14 markus 137: ssh_close_authentication_connection(auth);
1.5 markus 138: BN_clear_free(challenge);
1.1 markus 139: debug("RSA authentication accepted by server.");
140: return 1;
141: }
142: /* Otherwise it should return failure. */
143: if (type != SSH_SMSG_FAILURE)
144: packet_disconnect("Protocol error waiting RSA auth response: %d",
145: type);
146: }
1.14 markus 147: ssh_close_authentication_connection(auth);
1.1 markus 148: BN_clear_free(challenge);
149: debug("RSA authentication using agent refused.");
150: return 0;
151: }
152:
153: /*
154: * Computes the proper response to a RSA challenge, and sends the response to
155: * the server.
156: */
1.35 itojun 157: static void
1.1 markus 158: respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
159: {
1.13 markus 160: u_char buf[32], response[16];
1.73 markus 161: struct ssh_digest_ctx *md;
1.1 markus 162: int i, len;
163:
164: /* Decrypt the challenge using the private key. */
1.21 markus 165: /* XXX think about Bleichenbacher, too */
166: if (rsa_private_decrypt(challenge, challenge, prv) <= 0)
167: packet_disconnect(
168: "respond_to_rsa_challenge: rsa_private_decrypt failed");
1.1 markus 169:
170: /* Compute the response. */
171: /* The response is MD5 of decrypted challenge plus session id. */
172: len = BN_num_bytes(challenge);
1.61 djm 173: if (len <= 0 || (u_int)len > sizeof(buf))
1.21 markus 174: packet_disconnect(
175: "respond_to_rsa_challenge: bad challenge length %d", len);
1.1 markus 176:
177: memset(buf, 0, sizeof(buf));
178: BN_bn2bin(challenge, buf + sizeof(buf) - len);
1.73 markus 179: if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
180: ssh_digest_update(md, buf, 32) < 0 ||
181: ssh_digest_update(md, session_id, 16) < 0 ||
182: ssh_digest_final(md, response, sizeof(response)) < 0)
183: fatal("%s: md5 failed", __func__);
184: ssh_digest_free(md);
1.1 markus 185:
186: debug("Sending response to host key RSA challenge.");
187:
188: /* Send the response back to the server. */
189: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
190: for (i = 0; i < 16; i++)
191: packet_put_char(response[i]);
192: packet_send();
193: packet_write_wait();
194:
1.74 ! djm 195: explicit_bzero(buf, sizeof(buf));
! 196: explicit_bzero(response, sizeof(response));
! 197: explicit_bzero(&md, sizeof(md));
1.1 markus 198: }
199:
200: /*
201: * Checks if the user has authentication file, and if so, tries to authenticate
202: * the user using it.
203: */
1.35 itojun 204: static int
1.38 markus 205: try_rsa_authentication(int idx)
1.1 markus 206: {
207: BIGNUM *challenge;
1.36 markus 208: Key *public, *private;
1.38 markus 209: char buf[300], *passphrase, *comment, *authfile;
1.65 dtucker 210: int i, perm_ok = 1, type, quit;
1.1 markus 211:
1.38 markus 212: public = options.identity_keys[idx];
213: authfile = options.identity_files[idx];
214: comment = xstrdup(authfile);
215:
1.1 markus 216: debug("Trying RSA authentication with key '%.100s'", comment);
217:
218: /* Tell the server that we are willing to authenticate using this key. */
219: packet_start(SSH_CMSG_AUTH_RSA);
220: packet_put_bignum(public->rsa->n);
221: packet_send();
222: packet_write_wait();
223:
224: /* Wait for server's response. */
1.47 markus 225: type = packet_read();
1.1 markus 226:
227: /*
1.62 djm 228: * The server responds with failure if it doesn't like our key or
229: * doesn't support RSA authentication.
1.1 markus 230: */
231: if (type == SSH_SMSG_FAILURE) {
232: debug("Server refused our key.");
1.71 djm 233: free(comment);
1.1 markus 234: return 0;
235: }
236: /* Otherwise, the server should respond with a challenge. */
237: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
238: packet_disconnect("Protocol error during RSA authentication: %d", type);
239:
240: /* Get the challenge from the packet. */
1.43 markus 241: if ((challenge = BN_new()) == NULL)
242: fatal("try_rsa_authentication: BN_new failed");
1.46 markus 243: packet_get_bignum(challenge);
1.45 markus 244: packet_check_eom();
1.1 markus 245:
246: debug("Received RSA challenge from server.");
247:
248: /*
1.38 markus 249: * If the key is not stored in external hardware, we have to
250: * load the private key. Try first with empty passphrase; if it
1.1 markus 251: * fails, ask for a passphrase.
252: */
1.52 aaron 253: if (public->flags & KEY_FLAG_EXT)
1.38 markus 254: private = public;
255: else
1.65 dtucker 256: private = key_load_private_type(KEY_RSA1, authfile, "", NULL,
257: &perm_ok);
258: if (private == NULL && !options.batch_mode && perm_ok) {
1.36 markus 259: snprintf(buf, sizeof(buf),
260: "Enter passphrase for RSA key '%.100s': ", comment);
261: for (i = 0; i < options.number_of_password_prompts; i++) {
1.1 markus 262: passphrase = read_passphrase(buf, 0);
1.36 markus 263: if (strcmp(passphrase, "") != 0) {
264: private = key_load_private_type(KEY_RSA1,
1.65 dtucker 265: authfile, passphrase, NULL, NULL);
1.36 markus 266: quit = 0;
267: } else {
268: debug2("no passphrase given, try next key");
269: quit = 1;
270: }
1.74 ! djm 271: explicit_bzero(passphrase, strlen(passphrase));
1.71 djm 272: free(passphrase);
1.36 markus 273: if (private != NULL || quit)
274: break;
275: debug2("bad passphrase given, try again...");
1.1 markus 276: }
277: }
278: /* We no longer need the comment. */
1.71 djm 279: free(comment);
1.36 markus 280:
281: if (private == NULL) {
1.65 dtucker 282: if (!options.batch_mode && perm_ok)
1.36 markus 283: error("Bad passphrase.");
284:
285: /* Send a dummy response packet to avoid protocol error. */
286: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
287: for (i = 0; i < 16; i++)
288: packet_put_char(0);
289: packet_send();
290: packet_write_wait();
291:
292: /* Expect the server to reject it... */
1.47 markus 293: packet_read_expect(SSH_SMSG_FAILURE);
1.36 markus 294: BN_clear_free(challenge);
295: return 0;
296: }
1.1 markus 297:
298: /* Compute and send a response to the challenge. */
299: respond_to_rsa_challenge(challenge, private->rsa);
300:
1.38 markus 301: /* Destroy the private key unless it in external hardware. */
302: if (!(private->flags & KEY_FLAG_EXT))
303: key_free(private);
1.1 markus 304:
305: /* We no longer need the challenge. */
306: BN_clear_free(challenge);
307:
308: /* Wait for response from the server. */
1.47 markus 309: type = packet_read();
1.1 markus 310: if (type == SSH_SMSG_SUCCESS) {
311: debug("RSA authentication accepted by server.");
312: return 1;
313: }
314: if (type != SSH_SMSG_FAILURE)
315: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
316: debug("RSA authentication refused.");
317: return 0;
318: }
319:
320: /*
321: * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
322: * authentication and RSA host authentication.
323: */
1.35 itojun 324: static int
1.29 markus 325: try_rhosts_rsa_authentication(const char *local_user, Key * host_key)
1.1 markus 326: {
327: int type;
328: BIGNUM *challenge;
329:
330: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
331:
332: /* Tell the server that we are willing to authenticate using this key. */
333: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
1.33 markus 334: packet_put_cstring(local_user);
1.29 markus 335: packet_put_int(BN_num_bits(host_key->rsa->n));
336: packet_put_bignum(host_key->rsa->e);
337: packet_put_bignum(host_key->rsa->n);
1.1 markus 338: packet_send();
339: packet_write_wait();
340:
341: /* Wait for server's response. */
1.47 markus 342: type = packet_read();
1.1 markus 343:
344: /* The server responds with failure if it doesn't admit our
345: .rhosts authentication or doesn't know our host key. */
346: if (type == SSH_SMSG_FAILURE) {
347: debug("Server refused our rhosts authentication or host key.");
348: return 0;
349: }
350: /* Otherwise, the server should respond with a challenge. */
351: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
352: packet_disconnect("Protocol error during RSA authentication: %d", type);
353:
354: /* Get the challenge from the packet. */
1.43 markus 355: if ((challenge = BN_new()) == NULL)
356: fatal("try_rhosts_rsa_authentication: BN_new failed");
1.46 markus 357: packet_get_bignum(challenge);
1.45 markus 358: packet_check_eom();
1.1 markus 359:
360: debug("Received RSA challenge for host key from server.");
361:
362: /* Compute a response to the challenge. */
1.29 markus 363: respond_to_rsa_challenge(challenge, host_key->rsa);
1.1 markus 364:
365: /* We no longer need the challenge. */
366: BN_clear_free(challenge);
367:
368: /* Wait for response from the server. */
1.47 markus 369: type = packet_read();
1.1 markus 370: if (type == SSH_SMSG_SUCCESS) {
371: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
372: return 1;
373: }
374: if (type != SSH_SMSG_FAILURE)
375: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
376: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
377: return 0;
378: }
379:
380: /*
381: * Tries to authenticate with any string-based challenge/response system.
382: * Note that the client code is not tied to s/key or TIS.
383: */
1.35 itojun 384: static int
1.32 markus 385: try_challenge_response_authentication(void)
1.1 markus 386: {
387: int type, i;
1.13 markus 388: u_int clen;
1.12 markus 389: char prompt[1024];
1.1 markus 390: char *challenge, *response;
1.40 markus 391:
392: debug("Doing challenge response authentication.");
393:
1.12 markus 394: for (i = 0; i < options.number_of_password_prompts; i++) {
395: /* request a challenge */
396: packet_start(SSH_CMSG_AUTH_TIS);
397: packet_send();
398: packet_write_wait();
1.1 markus 399:
1.47 markus 400: type = packet_read();
1.12 markus 401: if (type != SSH_SMSG_FAILURE &&
402: type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
403: packet_disconnect("Protocol error: got %d in response "
1.20 markus 404: "to SSH_CMSG_AUTH_TIS", type);
1.12 markus 405: }
406: if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
1.20 markus 407: debug("No challenge.");
1.12 markus 408: return 0;
409: }
410: challenge = packet_get_string(&clen);
1.45 markus 411: packet_check_eom();
1.16 markus 412: snprintf(prompt, sizeof prompt, "%s%s", challenge,
1.42 deraadt 413: strchr(challenge, '\n') ? "" : "\nResponse: ");
1.71 djm 414: free(challenge);
1.1 markus 415: if (i != 0)
416: error("Permission denied, please try again.");
1.12 markus 417: if (options.cipher == SSH_CIPHER_NONE)
1.53 itojun 418: logit("WARNING: Encryption is disabled! "
1.50 stevesk 419: "Response will be transmitted in clear text.");
1.12 markus 420: response = read_passphrase(prompt, 0);
421: if (strcmp(response, "") == 0) {
1.71 djm 422: free(response);
1.12 markus 423: break;
424: }
1.1 markus 425: packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
1.27 markus 426: ssh_put_password(response);
1.74 ! djm 427: explicit_bzero(response, strlen(response));
1.71 djm 428: free(response);
1.1 markus 429: packet_send();
430: packet_write_wait();
1.47 markus 431: type = packet_read();
1.1 markus 432: if (type == SSH_SMSG_SUCCESS)
433: return 1;
434: if (type != SSH_SMSG_FAILURE)
435: packet_disconnect("Protocol error: got %d in response "
1.20 markus 436: "to SSH_CMSG_AUTH_TIS_RESPONSE", type);
1.1 markus 437: }
438: /* failure */
439: return 0;
440: }
441:
442: /*
443: * Tries to authenticate with plain passwd authentication.
444: */
1.35 itojun 445: static int
1.1 markus 446: try_password_authentication(char *prompt)
447: {
1.47 markus 448: int type, i;
1.1 markus 449: char *password;
450:
451: debug("Doing password authentication.");
452: if (options.cipher == SSH_CIPHER_NONE)
1.53 itojun 453: logit("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
1.1 markus 454: for (i = 0; i < options.number_of_password_prompts; i++) {
455: if (i != 0)
456: error("Permission denied, please try again.");
457: password = read_passphrase(prompt, 0);
458: packet_start(SSH_CMSG_AUTH_PASSWORD);
1.27 markus 459: ssh_put_password(password);
1.74 ! djm 460: explicit_bzero(password, strlen(password));
1.71 djm 461: free(password);
1.1 markus 462: packet_send();
463: packet_write_wait();
464:
1.47 markus 465: type = packet_read();
1.1 markus 466: if (type == SSH_SMSG_SUCCESS)
467: return 1;
468: if (type != SSH_SMSG_FAILURE)
469: packet_disconnect("Protocol error: got %d in response to passwd auth", type);
470: }
471: /* failure */
472: return 0;
473: }
474:
475: /*
476: * SSH1 key exchange
477: */
478: void
479: ssh_kex(char *host, struct sockaddr *hostaddr)
480: {
481: int i;
482: BIGNUM *key;
1.43 markus 483: Key *host_key, *server_key;
1.1 markus 484: int bits, rbits;
485: int ssh_cipher_default = SSH_CIPHER_3DES;
1.13 markus 486: u_char session_key[SSH_SESSION_KEY_LENGTH];
487: u_char cookie[8];
488: u_int supported_ciphers;
489: u_int server_flags, client_flags;
1.59 avsm 490: u_int32_t rnd = 0;
1.1 markus 491:
492: debug("Waiting for server public key.");
493:
494: /* Wait for a public key packet from the server. */
1.47 markus 495: packet_read_expect(SSH_SMSG_PUBLIC_KEY);
1.1 markus 496:
497: /* Get cookie from the packet. */
498: for (i = 0; i < 8; i++)
499: cookie[i] = packet_get_char();
500:
501: /* Get the public key. */
1.43 markus 502: server_key = key_new(KEY_RSA1);
503: bits = packet_get_int();
1.46 markus 504: packet_get_bignum(server_key->rsa->e);
505: packet_get_bignum(server_key->rsa->n);
1.1 markus 506:
1.43 markus 507: rbits = BN_num_bits(server_key->rsa->n);
1.1 markus 508: if (bits != rbits) {
1.53 itojun 509: logit("Warning: Server lies about size of server public key: "
1.1 markus 510: "actual size is %d bits vs. announced %d.", rbits, bits);
1.53 itojun 511: logit("Warning: This may be due to an old implementation of ssh.");
1.1 markus 512: }
513: /* Get the host key. */
1.43 markus 514: host_key = key_new(KEY_RSA1);
515: bits = packet_get_int();
1.46 markus 516: packet_get_bignum(host_key->rsa->e);
517: packet_get_bignum(host_key->rsa->n);
1.1 markus 518:
1.43 markus 519: rbits = BN_num_bits(host_key->rsa->n);
1.1 markus 520: if (bits != rbits) {
1.53 itojun 521: logit("Warning: Server lies about size of server host key: "
1.1 markus 522: "actual size is %d bits vs. announced %d.", rbits, bits);
1.53 itojun 523: logit("Warning: This may be due to an old implementation of ssh.");
1.1 markus 524: }
525:
526: /* Get protocol flags. */
527: server_flags = packet_get_int();
528: packet_set_protocol_flags(server_flags);
529:
530: supported_ciphers = packet_get_int();
531: supported_authentications = packet_get_int();
1.45 markus 532: packet_check_eom();
1.1 markus 533:
534: debug("Received server public key (%d bits) and host key (%d bits).",
1.43 markus 535: BN_num_bits(server_key->rsa->n), BN_num_bits(host_key->rsa->n));
1.1 markus 536:
1.43 markus 537: if (verify_host_key(host, hostaddr, host_key) == -1)
1.41 markus 538: fatal("Host key verification failed.");
1.1 markus 539:
540: client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
541:
1.58 djm 542: derive_ssh1_session_id(host_key->rsa->n, server_key->rsa->n, cookie, session_id);
1.1 markus 543:
544: /*
545: * Generate an encryption key for the session. The key is a 256 bit
546: * random number, interpreted as a 32-byte key, with the least
547: * significant 8 bits being the first byte of the key.
548: */
549: for (i = 0; i < 32; i++) {
550: if (i % 4 == 0)
1.59 avsm 551: rnd = arc4random();
552: session_key[i] = rnd & 0xff;
553: rnd >>= 8;
1.1 markus 554: }
555:
556: /*
557: * According to the protocol spec, the first byte of the session key
558: * is the highest byte of the integer. The session key is xored with
559: * the first 16 bytes of the session id.
560: */
1.43 markus 561: if ((key = BN_new()) == NULL)
1.70 markus 562: fatal("ssh_kex: BN_new failed");
563: if (BN_set_word(key, 0) == 0)
564: fatal("ssh_kex: BN_set_word failed");
1.1 markus 565: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1.70 markus 566: if (BN_lshift(key, key, 8) == 0)
567: fatal("ssh_kex: BN_lshift failed");
568: if (i < 16) {
569: if (BN_add_word(key, session_key[i] ^ session_id[i])
570: == 0)
571: fatal("ssh_kex: BN_add_word failed");
572: } else {
573: if (BN_add_word(key, session_key[i]) == 0)
574: fatal("ssh_kex: BN_add_word failed");
575: }
1.1 markus 576: }
577:
578: /*
579: * Encrypt the integer using the public key and host key of the
580: * server (key with smaller modulus first).
581: */
1.43 markus 582: if (BN_cmp(server_key->rsa->n, host_key->rsa->n) < 0) {
1.1 markus 583: /* Public key has smaller modulus. */
1.43 markus 584: if (BN_num_bits(host_key->rsa->n) <
585: BN_num_bits(server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
586: fatal("respond_to_rsa_challenge: host_key %d < server_key %d + "
1.42 deraadt 587: "SSH_KEY_BITS_RESERVED %d",
1.43 markus 588: BN_num_bits(host_key->rsa->n),
589: BN_num_bits(server_key->rsa->n),
1.42 deraadt 590: SSH_KEY_BITS_RESERVED);
1.1 markus 591: }
1.43 markus 592: rsa_public_encrypt(key, key, server_key->rsa);
593: rsa_public_encrypt(key, key, host_key->rsa);
1.1 markus 594: } else {
595: /* Host key has smaller modulus (or they are equal). */
1.43 markus 596: if (BN_num_bits(server_key->rsa->n) <
597: BN_num_bits(host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
598: fatal("respond_to_rsa_challenge: server_key %d < host_key %d + "
1.42 deraadt 599: "SSH_KEY_BITS_RESERVED %d",
1.43 markus 600: BN_num_bits(server_key->rsa->n),
601: BN_num_bits(host_key->rsa->n),
1.42 deraadt 602: SSH_KEY_BITS_RESERVED);
1.1 markus 603: }
1.43 markus 604: rsa_public_encrypt(key, key, host_key->rsa);
605: rsa_public_encrypt(key, key, server_key->rsa);
1.1 markus 606: }
607:
608: /* Destroy the public keys since we no longer need them. */
1.43 markus 609: key_free(server_key);
610: key_free(host_key);
1.1 markus 611:
1.11 markus 612: if (options.cipher == SSH_CIPHER_NOT_SET) {
613: if (cipher_mask_ssh1(1) & supported_ciphers & (1 << ssh_cipher_default))
614: options.cipher = ssh_cipher_default;
1.60 markus 615: } else if (options.cipher == SSH_CIPHER_INVALID ||
1.10 markus 616: !(cipher_mask_ssh1(1) & (1 << options.cipher))) {
1.53 itojun 617: logit("No valid SSH1 cipher, using %.100s instead.",
1.7 markus 618: cipher_name(ssh_cipher_default));
619: options.cipher = ssh_cipher_default;
1.1 markus 620: }
621: /* Check that the selected cipher is supported. */
622: if (!(supported_ciphers & (1 << options.cipher)))
623: fatal("Selected cipher type %.100s not supported by server.",
1.42 deraadt 624: cipher_name(options.cipher));
1.1 markus 625:
626: debug("Encryption type: %.100s", cipher_name(options.cipher));
627:
628: /* Send the encrypted session key to the server. */
629: packet_start(SSH_CMSG_SESSION_KEY);
630: packet_put_char(options.cipher);
631:
632: /* Send the cookie back to the server. */
633: for (i = 0; i < 8; i++)
634: packet_put_char(cookie[i]);
635:
636: /* Send and destroy the encrypted encryption key integer. */
637: packet_put_bignum(key);
638: BN_clear_free(key);
639:
640: /* Send protocol flags. */
641: packet_put_int(client_flags);
642:
643: /* Send the packet now. */
644: packet_send();
645: packet_write_wait();
646:
647: debug("Sent encrypted session key.");
648:
649: /* Set the encryption key. */
650: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
651:
1.74 ! djm 652: /*
! 653: * We will no longer need the session key here.
! 654: * Destroy any extra copies.
! 655: */
! 656: explicit_bzero(session_key, sizeof(session_key));
1.1 markus 657:
658: /*
659: * Expect a success message from the server. Note that this message
660: * will be received in encrypted form.
661: */
1.47 markus 662: packet_read_expect(SSH_SMSG_SUCCESS);
1.1 markus 663:
664: debug("Received encrypted confirmation.");
665: }
666:
667: /*
668: * Authenticate user
669: */
670: void
1.30 markus 671: ssh_userauth1(const char *local_user, const char *server_user, char *host,
1.51 markus 672: Sensitive *sensitive)
1.1 markus 673: {
674: int i, type;
1.42 deraadt 675:
1.1 markus 676: if (supported_authentications == 0)
1.30 markus 677: fatal("ssh_userauth1: server supports no auth methods");
1.1 markus 678:
679: /* Send the name of the user to log in as on the server. */
680: packet_start(SSH_CMSG_USER);
1.33 markus 681: packet_put_cstring(server_user);
1.1 markus 682: packet_send();
683: packet_write_wait();
684:
685: /*
686: * The server should respond with success if no authentication is
687: * needed (the user has no password). Otherwise the server responds
688: * with failure.
689: */
1.47 markus 690: type = packet_read();
1.1 markus 691:
692: /* check whether the connection was accepted without authentication. */
693: if (type == SSH_SMSG_SUCCESS)
1.37 dugsong 694: goto success;
1.1 markus 695: if (type != SSH_SMSG_FAILURE)
1.37 dugsong 696: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", type);
1.42 deraadt 697:
1.1 markus 698: /*
699: * Try .rhosts or /etc/hosts.equiv authentication with RSA host
700: * authentication.
701: */
702: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1.30 markus 703: options.rhosts_rsa_authentication) {
1.51 markus 704: for (i = 0; i < sensitive->nkeys; i++) {
705: if (sensitive->keys[i] != NULL &&
706: sensitive->keys[i]->type == KEY_RSA1 &&
707: try_rhosts_rsa_authentication(local_user,
708: sensitive->keys[i]))
1.37 dugsong 709: goto success;
1.30 markus 710: }
1.1 markus 711: }
712: /* Try RSA authentication if the server supports it. */
713: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
714: options.rsa_authentication) {
715: /*
716: * Try RSA authentication using the authentication agent. The
717: * agent is tried first because no passphrase is needed for
718: * it, whereas identity files may require passphrases.
719: */
720: if (try_agent_authentication())
1.37 dugsong 721: goto success;
1.1 markus 722:
723: /* Try RSA authentication for each identity. */
724: for (i = 0; i < options.num_identity_files; i++)
1.28 markus 725: if (options.identity_keys[i] != NULL &&
726: options.identity_keys[i]->type == KEY_RSA1 &&
1.38 markus 727: try_rsa_authentication(i))
1.37 dugsong 728: goto success;
1.1 markus 729: }
1.20 markus 730: /* Try challenge response authentication if the server supports it. */
1.1 markus 731: if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
1.32 markus 732: options.challenge_response_authentication && !options.batch_mode) {
733: if (try_challenge_response_authentication())
1.37 dugsong 734: goto success;
1.1 markus 735: }
736: /* Try password authentication if the server supports it. */
737: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
738: options.password_authentication && !options.batch_mode) {
739: char prompt[80];
740:
1.23 itojun 741: snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
1.1 markus 742: server_user, host);
743: if (try_password_authentication(prompt))
1.37 dugsong 744: goto success;
1.1 markus 745: }
746: /* All authentication methods have failed. Exit with an error message. */
747: fatal("Permission denied.");
748: /* NOTREACHED */
1.37 dugsong 749:
750: success:
1.39 stevesk 751: return; /* need statement after label */
1.1 markus 752: }
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